finish lab3 exercise1

labcodes/lab3/kern/mm/vmm.c

@@ -396,6 +396,36 @@ do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr) {
         }
    }
 #endif
+    ptep = get_pte(mm->pgdir,addr,1);
+    if(ptep ==  NULL)
+    {
+        cprintf("create pte failed");
+        goto failed;
+    }
+
+    if(*ptep == 0)
+    {
+        struct Page * alloc_result = pgdir_alloc_page(mm->pgdir,addr,perm);
+        if(alloc_result == NULL)
+        {
+            goto failed;
+        }
+    }
+    else
+    {
+        if(swap_init_ok)
+        {
+            struct Page* page = NULL;
+            swap_in(mm,addr,&page);
+            //if(page_insert(mm->pgdir,))
+        }
+        else
+        {
+            cprintf("no swap_init_ok but ptep is %x, failed\n",*ptep);
+            goto failed;
+        }
+    }
+
    ret = 0;
 failed:
     return ret;